Yazid I was the second Umayyad caliph, ruling from 680 to 683 CE. He is best known for his role in the Battle of Karbala, where his forces killed Husayn ibn Ali, the grandson of the Prophet Muhammad. This event is significant in Islamic history, particularly for Shia Muslims, who view it as a symbol of martyrdom and resistance against tyranny. Yazid's reign was marked by political instability and conflict, including revolts against his rule. His leadership style and actions contributed to the growing divide between Sunni and Shia Muslims, shaping the future of Islamic governance and sectarian relations.